Superhard gouging cutter or shock stud for fixed cutter drill bit

ABSTRACT

A gouging cutter or shock stud for mounting in a drill bit includes: a substrate being cylindrical for at least a portion thereof; and a cap or head made from a superhard material, mounted to the substrate at an interface, having a working face formed in an end thereof opposite to the interface, and having a round periphery connecting the interface and the substrate. The working face has a central tip elevated at a height above a maximum height of the periphery. The working face has a plurality of plows and a plurality of ribs arranged therearound in an alternating fashion. The plows and the ribs each extend from the periphery of the cap inward and upward to the tip. The plows and ribs each have a pair of sides and an apical edge. The plows have a different shape than a shape of the ribs.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure generally relates to a superhard gouging cutter or shock stud for a fixed cutter drill bit.

Description of the Related Art

U.S. Pat. No. 6,510,910 discloses cutting elements for incorporation in a drill bit having a body with an end face interfacing with an ultra hard material cutting layer. A main depression having a nonplanar surface is formed on the substrate and extending to the peripheral edge of the substrate subjected to the highest impact loads during drilling. This edge is immediately below the edge of the cutting layer which makes direct contact with the earth formations during drilling. The main depression is formed by forming a plurality of secondary depressions or steps. A second main depression is formed by forming a plurality of secondary depressions or steps. The second main depression also extends to the peripheral edge of the substrate. An ultra hard material layer is bonded to the end face of the cutting element body over the main depressions.

U.S. Pat. No. 7,798,258 discloses a drill bit for cutting a borehole and including a bit body having a bit axis. In addition, the drill bit includes a rolling cone cutter mounted on the bit body. Further, the drill bit includes a cutter element having a base portion with a diameter and a cutting portion extending therefrom. The cutting portion including a first pair of flanking surfaces that taper towards one another to form a first elongate chisel crest, and a second pair of flanking surfaces that taper towards one another to form a second elongate chisel crest that intersects the first elongate chisel crest in top view. The first crest tangent angle at 10 percent of the diameter measured radially from the central axis on the first elongate chisel crest in profile view is greater than 75 degrees and less than or equal to 90 degrees.

U.S. Pat. No. 8,365,845 discloses a high impact resistant tool including a sintered polycrystalline diamond body bonded to a cemented metal carbide substrate at an interface, the body including a substantially pointed geometry with an apex, the apex including a curved surface that joins a leading side and a trailing side of the body at a first and second transitions respectively, an apex width between the first and second transitions is less than a third of a width of the substrate, and the body also includes a body thickness from the apex to the interface greater than a third of the width of the substrate.

U.S. Pat. No. 8,794,356 discloses an earth-boring tool including a body, one or more blades projecting outwardly from the body, and cutting elements carried by the blade. The cutting elements include at least one shearing cutting element and at least one gouging cutting element. Methods of forming an earth-boring tool include mounting a shearing cutting element including an at least substantially planar cutting face to a body of an earth-boring tool, and mounting a gouging cutting element including a non-planar cutting face to the body of the earth-boring tool. The gouging cutting element may be positioned on the body of the earth-boring tool such that the gouging cutting element will gouge formation material within a kerf cut in the formation material by the shearing cutting element, or between kerfs cut in the formation material by a plurality of shearing cutting elements.

U.S. Pat. No. 8,839,888 discloses a fixed bladed drill bit including a working surface having a plurality of blades converging at a center of the working surface and diverging towards a gauge of the bit. Each blade includes a plurality of pointed cutting elements and another plurality of shearing cutters. The plurality of shearing cutters includes a first shearing cutter on each blade that tracks the first shearing cutter on other blades along a common circular cutting path.

U.S. Pat. No. 8,887,837 discloses a downhole cutting tool including: a tool body; a plurality of blades extending azimuthally from the tool body; and a plurality of cutting elements disposed on the plurality of blades, the plurality of cutting elements including: at least two non-planar cutting elements comprising a substrate and a diamond layer having a non-planar cutting end, wherein at least one of the at least two conical cutting elements has a positive back rake angle or positive side rake angle, and at least one of the at least two non-planar cutting elements has a negative back rake angle or a negative side rake angle.

U.S. Pat. No. 9,062,505 discloses a method of laser cutting polycrystalline diamond tables and polycrystalline diamond compacts.

US 2018/0087325 discloses a cutting element including a supporting substrate exhibiting a three-dimensional, laterally elongate shape, and a cutting table of a polycrystalline hard material attached to the supporting substrate and comprising a non-planar cutting face.

SUMMARY OF THE DISCLOSURE

The present disclosure generally relates to a superhard gouging cutter or shock stud for a fixed cutter drill bit. In one embodiment, a gouging cutter or shock stud for mounting in a drill bit includes: a substrate being cylindrical for at least a portion thereof; and a cap or head made from a superhard material, mounted to the substrate at an interface, having a working face formed in an end thereof opposite to the interface, and having a round periphery connecting the interface and the substrate. The working face has a central tip elevated at a height above a maximum height of the periphery. The working face has a plurality of plows and a plurality of ribs arranged therearound in an alternating fashion. The plows and the ribs each extend from the periphery of the cap inward and upward to the tip. The plows and ribs each have a pair of sides and an apical edge. The plows have a different shape than a shape of the ribs.

In another embodiment, a gouging cutter or shock stud for mounting in a drill bit includes: a cylindrical substrate; and a head made from a superhard material, mounted to the substrate at an interface, and having a working face formed in an end thereof opposite to the interface. The working face has a central tip having a maximum height of the working face above the substrate. A plurality of pads and a plurality of slots are arranged around the head in an alternating fashion. The pads each extend from a periphery of the substrate inward and upward to the tip. The working face has protruding borders formed between the pads. The slots each extend from the periphery inward. Each border extends from an inner end of the respective slot to the central tip.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

FIGS. 1A-1D illustrate a superhard polycrystalline gouging cutter for a fixed cutter drill bit, according to one embodiment of the present disclosure.

FIGS. 2A-2D illustrate a superhard impregnated gouging cutter for a fixed cutter drill bit, according to another embodiment of the present disclosure.

FIGS. 3A-3D and 4A-4D illustrate a first drill bit having either one of the superhard gouging cutters, according to another embodiment of the present disclosure.

FIGS. 5A and 5B illustrate a second drill bit having either one of the superhard gouging cutters, according to another embodiment of the present disclosure.

FIGS. 6A-6D illustrate a superhard shock stud for a fixed cutter drill bit, according to another embodiment of the present disclosure.

FIGS. 7A and 7B illustrate a third drill bit having either one of the superhard gouging cutters and the superhard shock stud, according to another embodiment of the present disclosure.

FIGS. 7C and 7D illustrate a fourth drill bit having either one of the superhard gouging cutters and the superhard shock stud, according to another embodiment of the present disclosure.

FIGS. 8A and 8B illustrate a fifth drill bit having a modified gouging cutter, according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1A-1D illustrate a superhard polycrystalline gouging cutter 1 p for a fixed cutter drill bit 11 (FIG. 3A), according to one embodiment of the present disclosure. The gouging cutter 1 p may include a substrate 2 and a cap 3 mounted to the substrate. The cap 3 may be made from a polycrystalline superhard material, such as polycrystalline diamond (PCD), and the substrate may be made from a hard material, such as a cermet. The cermet may be a cemented carbide, such as a group VIIIB metal-tungsten carbide. The group VIIIB metal may be cobalt. The gouging cutter 1 p may be manufactured by a high pressure, high temperature (HPHT) sintering operation using either a belt press or a cubic press. A working face 3 w may then be formed in the cap 3 such as by laser cutting or electrical discharge machining.

The cap 3 may have an interface 4 with the substrate 2, the working face 3 w at an end thereof opposite to the interface, and a round periphery 3 s connecting the interface and the working face. The substrate 2 may have the interface 4 with the cap 3 and a mounting end opposite to the interface for being received in a pocket of the drill bit 11. The mounting end of the substrate 2 may have a chamfer 2 c formed in a periphery thereof. The interface 4 may have a planar base 4 b, a planar central tip 4 p, and a conical shoulder 4 s connecting the base and the tip. The interface 4 may be located in a conical portion of the substrate 2 and the mounting end may be located in a cylindrical portion of the substrate.

The cap 3 may have a central tip 3 t formed in the working face 3 w thereof and elevated at a height above a maximum height of the periphery 3 s. A height of the tip 3 t above the base 4 b of the interface 4 may range between one-fifth and four-fifths of a length of the gouging cutter 1 p. The cap 3 may include a plurality of plows 5 (four shown) formed in the working face 3 w thereof and a plurality of ribs 6 (four shown) formed in the working face thereof. The plows 5 and the ribs 6 may be arranged around the working face 3 w in an alternating fashion. The plows 5 and the ribs 6 may each extend from the periphery 3 s of the cap 3 transversely inward and longitudinally upward to the tip 3 t. The tip 3 t may be flat, may have a round-rectangular, such as round-square, shape, and may have rounded edge with a radius 7 a ranging between one-tenth of a millimeter and one-half of a millimeter. The tip 3 t may have a diagonal extending between the round corners with a length 7 b ranging between ten percent and forty percent of a diameter of the cap 3.

At the periphery 3 s of the cap 3, each rib 6 may have a triangular shape. At the periphery 3 s of the cap 3, each rib 6 may have a pair of base edges 6 b and an apical edge 6 a elevated above the base edges. Each rib 6 may also have a pair of sides 6 s formed between the respective base edges 6 b and the respective apical edge 6 a. The sides 6 s may each be triangular and each apical edge 6 a may be convex. Each apical edge 6 a may also be elevated above the respective sides 6 s at the periphery 3 s of the cap 3. Each base edge 6 b and each side 6 s may converge toward the apical edge 6 a as the respective rib 6 extends from the periphery 3 s of the cap 3 to a respective junction 6 j located between the periphery of the cap and the tip 3 t thereof. Each apical edge 6 a may extend with a constant shape and with a constant radial slope from the periphery 3 s to the respective junction 6 j. Each apical edge 6 a may then radially converge and extend with an exponential radial slope from the respective junction 6 j to the tip 3 t. Each apical edge 6 a may then terminate at a side of the tip 3 t. Each apical edge 6 a may be round with a radius 7 c ranging between one-quarter of a millimeter and one millimeter.

The plows 5 may have a different shape from a shape of the ribs 6. At the periphery 3 s of the cap 3, each plow 5 may have a sinusoidal shape. Each plow 5 may share one of the base edges 6 b of each adjacent rib 6 and may have an apical edge 5 a elevated above the base edges. At the periphery 3 s of the cap 3, a height of each rib apical edge 6 a above the interface 4 may be greater than a height of each plow apical edge 5 a there-above and a circumferential width of each rib may be greater than a circumferential width of each plow. Each plow 5 may also have a pair of sides 5 s and each plow apical edge 5 a may also be elevated above the respective sides 5 s at the periphery 3 s of the cap 3. From the periphery 3 s of the cap 3 to the junctions 6 j, the sides 5 s of each plow 5 may be formed between the respective base edges 6 b and the respective apical edge 5 a. Each plow side 5 s may be concave and the apical edge 5 a thereof may be convex. Each plow apical edge 5 a may extend from the periphery 3 s to the tip 3 t with a constant shape and with a constant radial inclination angle 7 d. The radial inclination angle 7 d may range between twenty degrees and sixty degrees. Each plow apical edge 5 a may then terminate at a respective round corner of the tip 3 t. Each plow apical edge 5 a may be round with a radius 7 e ranging between three-eighths of a millimeter and one point five millimeters.

Each plow side 5 s may extend with a constant shape and with a constant radial slope from the periphery 3 s of the cap 3 to the respective junction 6 j. Each plow side 5 s may then be formed between the adjacent rib apical edge 6 a and the adjacent plow apical edge 5 a from the respective junction 6 j to the tip 3 t. Each plow side 5 s may then terminate at a side of the tip 3 t. Each plow side 5 s may have a fillet with a radius 7 f ranging between one millimeter and four millimeters. Each plow 5 may have a maximum thickness 7 g at the apical edge 5 a ranging between one millimeter and four millimeters. The maximum thickness 7 g may be constant except for portions thereof adjacent to the periphery 3 s of the cap 3 and the tip 3 t of the working face 3 w.

Alternatively, the tip 3 t may be rounded or sharp. Alternatively, each plow side 5 s may be polygonal instead of concave with a circumferential inclination angle ranging between thirty degrees and eighty degrees.

FIGS. 2A-2D illustrate a superhard impregnated gouging cutter 1 g for a fixed cutter drill bit 11, according to another embodiment of the present disclosure. The gouging cutter 1 g may include a cylindrical substrate 8 and a head 9 mounted to the substrate. The head 9 may be made from a composite material, such as a cermet impregnated with superhard material, such as monocrystalline or thermally stable polycrystalline diamond. The cermet may be a cemented carbide and the diamond may be dispersed therein at a content ranging between twenty-five percent and sixty percent by volume. The substrate 8 may be similar to the substrate 2, discussed above. The gouging cutter 1 g may be manufactured by a hot isostatic pressing operation. The working face 3 w may then be formed in the head 9 such as by laser cutting or electrical discharge machining.

The head 9 may have an interface 10 with the substrate 8, the working face 3 w at an end thereof opposite to the interface, and the periphery 3 s connecting the interface and the working face. The substrate 8 may have the interface 10 with the head 9 and a mounting end opposite to the interface for being received in a pocket of the drill bit 11. The mounting end of the substrate 8 may have a chamfer 8 c formed in a periphery thereof. The interface 10 may be planar. To facilitate manufacturing, the substrate 8 may have a lip 8 p extending along a periphery thereof between the interface and the chamfer 8 c. The head 9 may have the central tip 3 t formed in the working face 3 w thereof and elevated at a height above a maximum height of the periphery 3 s. The height of the tip 3 t above the interface 10 may range between one-third and one hundred percent of a length of the substrate 8. The head 9 may include the plurality of plows 6 (four shown) formed in the working face 3 w thereof and the plurality of ribs 5 (four shown) formed in the working face thereof.

FIGS. 3A-3D and 4A-4D illustrate a first drill bit 11 having either one 1 of the gouging cutters 1 p,g, according to another embodiment of the present disclosure. The drill bit 11 may include a cutting face 12, a bit body 13, a shank 14, and a gage section 15. A lower portion of the bit body 13 may be made from a composite material, such as a ceramic and/or cermet matrix powder infiltrated by a metallic binder, and an upper portion of the bit body 13 may be made from a softer material than the composite material of the upper portion, such as a metal or alloy shoulder powder infiltrated by the metallic binder. The bit body 13 may be mounted to the shank 14 during molding thereof. The shank 14 may be tubular and made from a metal or alloy, such as steel, and have a coupling, such as a threaded pin, formed at an upper end thereof for connection of the drill bit 11 to a drill collar (not shown). The shank 14 may have a flow bore formed therethrough and the flow bore may extend into the bit body 13 to a plenum (not shown) thereof. The cutting face 12 may form a lower end of the drill bit 1 and the gage section 15 may form at an outer portion thereof.

Alternatively, the bit body 13 may be metallic, such as being made from steel, and may be hardfaced. The metallic bit body may be connected to a modified shank by threaded couplings and then secured by a weld or the metallic bit body may be monoblock having an integral body and shank.

The cutting face 12 may include one or more (three shown) primary blades 16 p, one or more (four shown) secondary blades 16 s, fluid courses formed between the blades, leading cutters 17, backup gouging cutters 1, and shock studs 18. The cutting face 12 may have one or more sections, such as an inner cone 12 c, an outer shoulder 12 s, and an intermediate nose 12 n between the cone and the shoulder sections. The blades 16 may be disposed around the cutting face and each blade may be formed during molding of the bit body 13 and may protrude from a bottom of the bit body. The primary blades 16 p and the secondary blades 16 s may be arranged around the cutting face 12 in an alternating fashion. The primary blades 16 p may each extend from a center of the cutting face 12, across the cone 12 c and nose 12 n sections, along the shoulder section 12 s, and to the gage section 15. The secondary blades 16 s may each extend from a periphery of the cone section 12 c, across the nose section 12 n, along the shoulder section 12 s, and to the gage section 15. Each blade 16 may extend generally radially across the cone 12 c (primary only) and nose 12 n sections with a slight spiral curvature and along the shoulder section 12 s generally longitudinally with a slight helical curvature.

Each blade 16 may be made from the same material as the lower portion of the bit body 13. The leading cutters 17 may be pre-formed, such as by high pressure and temperature sintering, and mounted, such as by brazing, in respective leading pockets formed in the blades 16 adjacent to the leading edges thereof. The leading cutters 17 may be mounted into the leading pockets after infiltration of the bit body 13. Each blade 16 may have a bearing face 16 f extending between a leading edge and a trailing edge thereof. Each leading cutter 17 may be a shear cutter and include a superhard cutting table, such as polycrystalline diamond, attached to a hard substrate, such as a cermet, thereby forming a compact, such as a polycrystalline diamond compact (PDC). The cermet may be a carbide cemented by a Group VIIIB metal, such as cobalt. The substrate and the cutting table may each be solid and cylindrical and a diameter of the substrate may be equal to a diameter of the cutting table.

Starting in the nose section 12 n, each blade 16 may have a row of backup pockets formed in the bearing face 16 f thereof and extending therealong through most of the shoulder section 12 s. Each backup pocket may be aligned with or slightly offset from a respective leading pocket. The gouging cutters 1 may be mounted into the backup pockets after infiltration of the bit body 13 and may be mounted by brazing or interference fit. Each blade 16 may have an orientation guide 19, such as a hole, formed in the bearing face 16 f thereof adjacent to each backup pocket. During mounting, a technician or robot may align one of the plows 5 of each gouging cutter 1 with the respective orientation guide 19, thereby ensuring the proper orientation of the gouging cutter. The proper orientation may be where the plow 5 adjacent to the respective leading cutter 17 has a two-dimensionally projected centerline tangent to a circle concentric with a center of the cutting face 12 and intersecting a center of a two-dimensional projection of the working face 3 w.

The shock studs 18 may protrude from the bearing face 16 f of each primary blade 16 p in the cone section 12 c and may be aligned with or slightly offset from a respective leading cutter 17. The shock studs 18 may be inserted into a mold (not shown) used to infiltrate the bit body 13 and blades 16 such that the shock studs are mounted to the blades by bonding during infiltration thereof or the shock studs may be mounted into pockets formed in the bearing 16 f face thereof, such as by brazing or interference fit. Each shock stud 18 may include a cylindrical base portion (not shown) and a non-planar working portion. The non-planar working portion may be dome shaped. The cylindrical base portion may be disposed in the respective pocket and the working portion may extend therefrom. Each shock stud may be from a cermet, such as a cemented carbide.

Each of the cutters 1,17 and shock studs 2 may have an exposed portion extending below the bearing faces 16 f. The gouging cutters 1 and almost all of the leading cutters 17 may have equal exposure 20 e demarcated by a primary exposure line 20 n in FIG. 3C (profile of one of the primary blades 16 p) and 4C (profile of all of the blades 16). The shock studs 18 and a first leading cutter 17 on each primary blade may have an exposure 20 e slightly less than the primary exposure 20 n. Positions of the cutters 1,17 may be staggered across the blades 16 to obtain complete and overlapping coverage (FIG. 4C).

Each leading cutter 17 may be tilted about a radial rake axis from the center of the cutting face 12 to the center thereof (perpendicular to the page in FIG. 4D) by a back rake angle 22 b. The back rake angle 22 b may range between ten degrees and thirty degrees. Each gouging cutter 1 may be tilted about the radial rake axis by a forward rake angle 22 f which may range between one degree and ten degrees or a back rake angle (not shown) ranging between one degree and ten degrees.

Alternatively, each gouging cutter 1 may not be tilted about the radial rake axis.

One or more (seven shown) ports 21 p may be formed in the bit body 13 and each port may extend from the plenum and through the bottom of the bit body to discharge drilling fluid (not shown) along the fluid courses. A nozzle 21 n may be disposed in each port 21 p and fastened to the bit body 13. Each nozzle 21 p may be fastened to the bit body 13 by having a threaded coupling formed in an outer surface thereof and each port 21 p may be a threaded socket for engagement with the respective threaded coupling. The ports 21 p may include an inner set of one or more (three shown) ports disposed in the cone section 12 c and an outer set of one or more (four shown) ports disposed in the nose section 12 n and/or shoulder section 12 s. Each inner port 21 p may be disposed between an inner end of a respective secondary blade 16 s and the center of the cutting face 12.

The gage section 15 may define a gage diameter of the drill bit 11. The gage section 15 may include a plurality of gage pads 15 p, such as one gage pad for each blade 16, and junk slots formed between the gage pads. The junk slots may be in fluid communication with the fluid courses formed between the blades 16. The gage pads 15 p may be disposed around the gage section 15 and each pad may be formed during molding of the bit body 13 and may protrude from the outer portion of the bit body. Each gage pad 15 p may be made from the same material as the bit body 13 and each gage pad may be formed integrally with a respective blade 16. Each gage pad 15 p may extend upward from an end of the respective blade 16 in the shoulder section 12 s to an exposed outer surface of the shank 14. Each gage pad 15 p may include a transition portion located adjacent to the shoulder section 12 s, a full diameter portion extending from the transition portion, and a tapered portion extending from the full diameter portion to the shank 14.

The tapered portion of each gage pad 15 p may have a pocket formed in a leading edge thereof. An up-drill cutter 15 u may be mounted in each pocket of the tapered portion. Each up-drill cutter 15 u may be mounted into the respective pocket by brazing. Each up-drill cutter 15 u may be a shear cutter, similar to the leading cutters 17, discussed above. Positions of the up-drill cutters 15 u may be staggered across the gage pads 15 p to obtain complete and overlapping coverage.

Alternatively, the gage pads 15 p may have gage protectors embedded therein. Each gage protector may be a thermally stable polycrystalline diamond.

In use (not shown), the drill bit 11 may be assembled with one or more drill collars, such as by threaded couplings, thereby forming a bottomhole assembly (BHA) (not shown). The BHA may be connected to a bottom of a pipe string, such as drill pipe or coiled tubing, thereby forming a drill string. The BHA may further include a steering tool, such as a bent sub or rotary steering tool, for drilling a deviated portion of the wellbore. The pipe string may be used to deploy the BHA into the wellbore. The drill bit 1 may be rotated, such as by rotation of the drill string from a rig (not shown) and/or by a drilling motor (not shown) of the BHA, while drilling fluid, such as mud, may be pumped down the drill string. A portion of the weight of the drill string may be set on the drill bit 1. The drilling fluid may be discharged by the nozzles 21 n and carry cuttings up an annulus formed between the drill string and the wellbore and/or between the drill string and a casing string and/or liner string.

As the drill bit 11 engages a rock formation (not shown) adjacent to the wellbore, each leading cutter 17 may shear the formation while the respective gouging cutter 1 may gouge and/or crush the formation, thereby resulting in a dual-mode attack on the formation.

FIGS. 5A and 5B illustrate a second drill bit 23 having either one 1 of the superhard gouging cutters 1 p,g, according to another embodiment of the present disclosure. The second drill bit 23 may be similar to the first drill bit 11 except for having an alternative cutting face. The alternative cutting face may be similar to the cutting face 12 except for having modified primary blades 23 p instead of the primary blades 16 p, modified shock studs 23 d instead of the shock studs 18, and modified secondary blades 23 s instead of the secondary blades 16 s. The modified primary blades 23 p may be similar to the primary blades 16 p except for having additional backup pockets extending across the nose section thereof and even into the cone section thereof and additional gouging cutters 1 mounted into the additional backup pockets. Further, the modified primary blades 23 p may have the modified shock studs 1 d molded into or mounted into the cone section thereof instead of the shock studs 18.

The modified shock studs 23 d may be similar to either one of the gouging cutters 1 p,d except for having a smaller diameter and length in order to fit in the more confined cone section of the modified primary blades 23 p. As with the shock studs 18, the modified shock studs 23 d may have an exposure 20 e slightly less than the primary exposure 20 n. The modified shock studs 23 d may be placed in the second drill bit 23 with a random orientation. The modified secondary blades 23 s may be similar to the secondary blades 16 s except for having the gouging cutters 1 with an exposure 20 e slightly less than the primary exposure 20 n. The exposure 20 e of the gouging cutters 1 may also be slightly less than the primary exposure 20 n for the modified primary blades 23 p.

FIGS. 6A-6D illustrate a superhard shock stud 24 for a fixed cutter drill bit 32, according to another embodiment of the present disclosure. The shock stud 24 may include a cylindrical substrate 25 and a head 26 mounted to the substrate. The head 26 may be made from the impregnated material, discussed above for the head 9. The substrate 25 may be similar to the substrate 2, discussed above. The shock stud 24 may be manufactured by a hot isostatic pressing operation. A working face 26 w may then be formed in the head 26 such as by laser cutting or electrical discharge machining.

The head 26 may have an interface 27 with the substrate 25, the working face 26 w at an end thereof opposite to the interface. The substrate 25 may have the interface 27 with the head 26 and a mounting end opposite to the interface for being received in a pocket of the drill bit 32. The mounting end of the substrate 25 may have a chamfer 25 c formed in a periphery thereof. The interface 27 may be planar. To facilitate manufacturing, the substrate 25 may have a lip 25 p extending along a periphery 25 s thereof between the interface and the chamfer 25 c.

The head 26 may include a plurality of pads 28 (four shown) and a plurality of slots 29 (four shown). The pads 28 and the slots 29 may be arranged around the head 26 in an alternating fashion. Each pad 28 may extend from the periphery 25 s of the substrate 25 transversely inward and longitudinally upward to a tip 26 t of the working face 26 w. The tip 26 t may be flat or slightly convex, may have a rectangular, such as square, shape, and may have rounded edge with a radius 30 a ranging between one-tenth of a millimeter and one-half of a millimeter. If the tip is 26 t slightly convex, the tip may have a large radius 30 b, such as greater than or equal to one-half of a diameter of the substrate 25. The tip 26 t may have a width 30 c ranging between five percent and twenty-five percent of a diameter of the substrate 25. An elevation of the tip 26 t above the interface 27 may be a maximum height of the working face 26 w. The height of the tip 26 t above the interface 27 may range between one-third and one hundred percent of a length of the substrate 25.

The pads 28 may be separated by the slots 29 and by protruding borders 31 formed in the working face 26 w. Each pad 28 may have a rectangular outer portion 28 o and a triangular inner portion 28 n. The outer portions may be separated by the slots 29 and the inner portions 28 n may be separated by the protruding borders 31. The protruding borders 31 may each be rounded or chamfered. The working face of each pad 28 may extend from the periphery 25 s of the substrate 25 to the tip 26 t with a constant radial inclination angle 30 d. The radial inclination angle 30 d may range between twenty degrees and sixty degrees. Each pad 28 may then terminate at a side of the tip 26 t. Each pad 28 may have a round base edge extending from the interface 27 and having a radius 30 e ranging between one-tenth and one-half of a millimeter. Each outer portion 28 o of the respective pad 28 may have a round outer edge conforming to the periphery 25 s of the substrate 25, a pair of transversely extending sides, and rounded corners connecting the edge and the sides. The base edge of each pad 28 at the rounded corners may have a radius 30 f ranging between one-quarter of a millimeter and one millimeter.

Each slot 29 may extend from the periphery 25 s of the substrate 25 transversely inward by a radial distance 30 g ranging between one-tenth and four-tenths of a diameter of the substrate 25 s. Each slot 29 may expose an upper face of the substrate 25 and have a maximum height 30 h located adjacent to a respective border 31. The maximum height 30 h may range between three-tenths and eight-tenths of the height of the tip 26 t above the interface 27. The base edge of each pad 28 adjacent to the respective slot 29 may have a parabolic shape with a lower vertex having a radius 30 j ranging between five-eighths of a millimeter and two point five millimeters. Each slot may also have an upper vertex adjacent to the working face of the respective pad. Each border 31 may extend from the upper vertex of the respective slot 29 and may terminate at a respective rounded corner of the tip 26 t.

FIGS. 7A and 7B illustrate a third drill bit 32 having either one 1 of the superhard gouging cutters 1 p,g and the superhard shock stud 24, according to another embodiment of the present disclosure. The third drill bit 32 may be similar to the first drill bit 11 except for having an alternative cutting face. The alternative cutting face may be similar to the cutting face 12 except for having modified primary blades 32 p instead of the primary blades 16 p and the superhard shock studs 24 instead of the shock studs 18. The modified primary blades 32 p may be similar to the primary blades 16 p except for having the superhard shock studs 24 molded into or mounted into the cone section thereof instead of the shock studs 18. As with the shock studs 18, the superhard shock studs 24 may have an exposure 20 e slightly less than the primary exposure 20 n. The superhard shock studs 24 may be placed in the third drill bit 32 with a random orientation.

FIGS. 7C and 7D illustrate a fourth drill bit 33 having either one 1 of the superhard gouging cutters 1 p,g and the superhard shock stud 24, according to another embodiment of the present disclosure. The fourth drill bit 33 may be similar to the first drill bit 11 except for having an alternative cutting face. The alternative cutting face may be similar to the cutting face 12 except for having modified primary blades 33 p instead of the primary blades 16 p, the superhard shock studs 24 instead of the shock studs 18, and modified secondary blades 33 s instead of the secondary blades 16 s. The modified primary blades 33 p may be similar to the primary blades 16 p except for each having only a pair of backup pockets in the nose section thereof and a pair of gouging cutters 1 disposed therein. Further, the modified primary blades 33 p may have the superhard shock studs 24 molded into or mounted into the cone section thereof instead of the shock studs 18.

Instead of being aligned with a respective leading cutter 17, each gouging cutter 1 and an outer one of the shock studs 24 on each modified primary blade 33 p may be located at an interruptive position between a respective pair of leading cutters. As with the shock studs 18, the superhard shock studs 24 may have an exposure 20 e slightly less than the primary exposure 20 n. The superhard shock studs 24 may be placed in the fourth drill bit 33 with a random orientation. The modified secondary blades 33 s may be similar to the secondary blades 16 s except for having the gouging cutters 1 and their associated backup pockets omitted. The exposure 20 e of an inner one of the gouging cutters 1 on each modified primary blade 33 p may also be slightly less than the primary exposure 20 n for the modified primary blades. The exposure 20 e of an outer one of the gouging cutters 1 on each modified primary blade 33 p may be equal to the primary exposure 20 n for the modified primary blades 23 p.

FIGS. 8A and 8B illustrate a fifth drill bit 34 having a modified gouging cutter 35, according to another embodiment of the present disclosure. The fifth drill bit 34 may be similar to the first drill bit 11 except for having an alternative cutting face 34 f and an alternative gage section. The alternative cutting face may 34 f be similar to the cutting face 12 except for having modified primary blades 36 p instead of the primary blades 16 p, the modified gouging cutters 35 instead of the gouging cutters 1, and modified secondary blades 36 s instead of the secondary blades 16 s.

The modified blades 36 p,s may be similar to the blades 16 except for having additional backup pockets extending across the shoulder and nose sections thereof, having the modified gouging cutters 35 mounted into the backup pockets in the shoulder section, and having backup shear cutters 37 mounted into the backup pockets in the nose section, such as by brazing. Further, each blade blades 36 p,s may have a second row of backup pockets formed in the bearing face thereof along most of the shoulder section thereof. Backup shear cutters 37 may also be mounted into the second row of backup cutters, such as by brazing. Each second backup pocket may be aligned with or slightly offset from a respective leading pocket and a respective (first) backup pocket. Each backup cutter 37 may be a shear cutter similar to the leading cutter 17, discussed above.

The modified gouging cutters 35 may be similar to the superhard shock studs 24 except for having a larger diameter and greater length accommodated by the more spacious shoulder section of the modified blades 36 p,s. Further, each first backup pocket in the shoulder section may have the orientation guides 19 formed in the bearing face thereof adjacent to the respective first backup pockets. The orientation guides 19 may be used to align one of the pads of each modified gouging cutters 35 with the respective orientation guide, thereby ensuring the proper orientation of the gouging cutter. The proper orientation may be where the pad adjacent to the respective leading cutter 17 has a two-dimensionally projected centerline tangent to a circle concentric with a center of the cutting face 34 f and intersecting a center of a two-dimensional projection of the working face. The modified gouging cutters 35 may have an exposure slightly less than the primary exposure.

The alternative gage section may be similar to the gage section 15 except for the omission of the up-drill cutters, having extended transition portions, and having a pocket formed in a leading edge of each transition portion. A gage trimmer 38 may be mounted in each pocket of the transition portion, such as by brazing and may have a flat formed therein to adjust a size of the fifth drill bit 34. Each gage trimmer 38 may be a shear cutter similar to the leading cutter 17, discussed above.

In another embodiment (not shown), a sixth drill bit may have either one 1 of the superhard gouging cutters 1 p,g or the superhard shock stud 24 as leading cutters. A plurality of any of these cutters 1 p,g or shock studs 24 may be disposed in the leading pockets instead of the leading cutters 17. These cutters may be oriented at the forward rake angle 22 f (or back rake angle) as discussed above.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope of the invention is determined by the claims that follow. 

1. A gouging cutter or shock stud for mounting in a drill bit, comprising: a substrate being cylindrical for at least a portion thereof; and a cap or head made from a superhard material, mounted to the substrate at an interface, having a working face formed in an end thereof opposite to the interface, and having a round periphery connecting the interface and the substrate, wherein: the working face has a central tip elevated at a height above a maximum height of the periphery, the working face has a plurality of plows and a plurality of ribs arranged therearound in an alternating fashion, the plows and the ribs each extend from the periphery of the cap inward and upward to the tip, the plows and ribs each have a pair of sides and an apical edge, and the plows have a different shape than a shape of the ribs.
 2. The gouging cutter or shock stud of claim 1, wherein, at the periphery, a height of each rib apical edge is greater than a height of each plow apical edge and a circumferential width of each rib is greater than a circumferential width of each plow.
 3. The gouging cutter or shock stud of claim 1, wherein the rib sides converge from the periphery toward the rib apical edge at a junction located between the periphery and the tip.
 4. The gouging cutter or shock stud of claim 2, wherein: the rib apical edges extend from the periphery to the junction with a constant shape and a constant slope, and the rib apical edges radially converge and extend with an exponential slope from the junction to the tip.
 5. The gouging cutter or shock stud of claim 1, wherein the plows have a sinusoidal shape and the ribs have a triangular shape.
 6. The gouging cutter or shock stud of claim 1, wherein: the tip is flat and has a round-rectangular shape, the plow apical edges terminate at round corners of the tip, the plow sides and the rib apical edges terminate at sides of the tip.
 7. The gouging cutter or shock stud of claim 1, wherein the cap or head is a cap made from a polycrystalline superhard material and the interface is non-planar.
 8. The gouging cutter or shock stud of claim 1, wherein the cap or head is a head made from a cermet impregnated with superhard material and the interface is planar.
 9. A bit for drilling a wellbore, comprising: a shank having a coupling formed at an upper end thereof; a body mounted to a lower end of the shank; and a cutting face forming a lower end of the bit and comprising: a blade protruding from the body; a leading cutter comprising: a substrate mounted in a pocket formed in a leading edge of the blade; and a cutting table made from a superhard material and mounted to the substrate; and the gouging cutter or shock stud of claim 1 mounted in a pocket formed in the bearing face of the blade.
 10. The bit of claim 9, wherein an orientation guide is formed in the bearing face adjacent to the pocket.
 11. The bit of claim 9, wherein the gouging cutter or shock stud is back raked or forward raked at an angle ranging between 1 degree and 10 degrees.
 12. The bit of claim 9, wherein the gouging cutter or shock stud has an exposure equal to or less than an exposure of the leading cutter.
 13. The bit of claim 9, wherein the gouging cutter or shock stud is aligned with the leading cutter.
 14. The bit of claim 9, wherein: the cutting face has a plurality of leading cutters mounted in respective pockets formed along the leading edge of the blade, and the gouging cutter or shock stud is located at an interruptive position between a pair of the leading cutters.
 15. The bit of claim 9, wherein: the cutting face has an inner cone section, an outer shoulder section, and an intermediate nose section, and the cutting face has a plurality of gouging cutter or shock studs mounted in respective pockets formed in the bearing face of the blade along the nose and shoulder sections.
 16. The bit of claim 9, wherein: the cutting face has an inner cone section, an outer shoulder section, and an intermediate nose section, and the cutting face has a plurality of gouging cutter or shock studs mounted in respective pockets formed in the bearing face of the blade along the cone, nose, and shoulder sections.
 17. The bit of claim 9, wherein: the cutting face has an inner cone section, an outer shoulder section, and an intermediate nose section, and the cutting face has a plurality of gouging cutter or shock studs mounted in respective pockets formed in the bearing face of the blade along the nose section.
 18. A bit for drilling a wellbore, comprising: a shank having a coupling formed at an upper end thereof; a body mounted to a lower end of the shank; and a cutting face forming a lower end of the bit and comprising: a blade protruding from the body; and the gouging cutter or shock stud of claim 1 mounted in a pocket formed in a leading edge of the blade.
 19. A gouging cutter or shock stud for mounting in a drill bit, comprising: a cylindrical substrate; and a head made from a superhard material, mounted to the substrate at an interface, and having a working face formed in an end thereof opposite to the interface, wherein: the working face has a central tip having a maximum height of the working face above the substrate, a plurality of pads and a plurality of slots are arranged around the head in an alternating fashion, the pads each extend from a periphery of the substrate inward and upward to the tip, the working face has protruding borders formed between the pads, the slots each extend from the periphery inward, and each border extends from an inner end of the respective slot to the central tip.
 20. The gouging cutter or shock stud of claim 19, wherein the slots each expose an upper face of the substrate. 